The project consists of 2 clinical trials each attempting to incite an immune response in patients with Medullary Thyroid Cancer designed to generate an immune response and evaluate clinical outcomes. The first trial involved the use of a therapeutic cancer vaccine that was developed in the NCI as part of CRADA. The second follow-up study involved a collaboration with Merck, evaluating pembrolizumab in patients with Medullary Thyroid Cancer, some of who previously have been treated with cancer vaccine to evaluate immunologic synergies.